Note: Descriptions are shown in the official language in which they were submitted.
. .
PCT/US2003/020464
CA 02492228 2004-12-31 Replacement Page
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Dental Modeling and Articulating System and Method
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to dental modeling and articulating
systems and
~5 methods. More particularly, the present invention relates to a hinge for
such a dental modeling
and articulating system and a thin membrane for such a dental modeling and
articulating system.
Related Art
The production of a dental prosthesis requires the production of a working
dental model
that is a substantially exact duplication of the patient's mouth, and upon
which the prosthesis
1.0 can be fabricated. Such dental prostheses can include crowns, bridges,
caps (substructure) for
CAD/CAM production, inlays, onlays and other restorative dental works.
One method of making a dental model is referred to as the "Double Pour Method"
or
"pindex method." In this method, once the model is poured and allowed time to
dry, it is
separated and trimmed; then holes are placed in the lower surface of the cast
followed by
15 inserting the pin with glue and placing the cast into second-pour stone
base. The disadvantages
of this process include: time consuming, troublesome dowel pin setup, and the
requirement for
two pours of casting material to create a base and a die. Moreover, this
method often involves
guesswork, since this method requires the technician to hand occlude two
separate casts
manually to set the bite. This guesswork will occasionally result in an
inaccurate reproduction
20 of the occlusal relationship of the mandibular and maxilly casts. This
inaccurate reproduction
will not match the original bites provided by the dentist at the time the
negative impression was
taken. An example of this method can be found in U.S. Pat. 4,734,033. This
method can use a
separate hinge that is separately attached to the stone bases or models. The
hinge can include an
adjustable ball-and-socket type connection that is rigidly fixed after the
stone bases or models
25 are aligned.
Another method is referred to as the "Single Pour Method" or "wet pinning
method." In
this method, a plastic tray support member replaces the stone base mentioned
above, so the
second pour stage is eliminated. As a result, the whole process of making a
dental model can be
considerably shortened. Moreover, it is possible to mount the case without
separating the upper
30 and lower cast from the impression so that the case is mounted with the
bite exactly as the
impression is provided by the dentist. This "Single Pour Method" or "wet
pinning technique"
can include two types. The first type is the "open cavity tray type" that 1)
can stabilize the
prosthesis element being worked on, without shifting, or prevent movement of
the prosthesis
dies with the help of a notched or arcuate cavity wall which is relatively
high; and 2) can
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2
eliminate the additional labor of registration pin hole drilling and the
pindexing process. The
disadvantages of this process include: 1 ) it can be difficult to control the
dies over the entire
process of die preparation, wax up, metal finish and porcelain build-up
because there is no pin
attached at the bottom of the prosthesis dies to hold to work with; 2) initial
removal of the entire
die from the tray can be difficult because the tray has comparatively high and
notched walls
necessitating the use of an extra accessory, like a special releasing device,
a stand, a mallet etc.,
and part of the cast can break while being released from the tray; and 3) the
initial stage of the
wet porcelain build up can be broken because the dies can be seated firmly by
a rail or spine that
snap fits or clicks into the tray. Examples of such-methods can be found in
U.S. Patents
5,306,145 and 6,099,305.
The second type is the "pin type", where the plastic tray support members have
plurality
of registration pin holes, and the master die from this system is convenient
to hold and work
with since there is at least one pin protruding from underneath each segmented
die. In addition,
the upper cast and lower cast are not separated from the impression until they
are articulated by
a hinge. Thus, the case is mounted with the bite exactly as the impression
provided by the
dentist. One disadvantage of this process include excessive holding of the
casting material stuck
in the registration holes because the semi-liquid model material tends to
creep through the
registration holes and harden. When the model material hardens, it gets stuck
in these holes,
making the initial release of the segmented dies from the tray support members
difficult. In
addition, it may be required to break the dies off the tray forcefully,
leaving tiny debris of
casting material from the breakage sitting between the dies and the tray
during the entire work
process, interfering with the proper relationship with the adjacent dies and
also the opposing
model. Another disadvantage with these methods is that they often have either
a flimsy hinge or
separate hinges that have to be connected to the main body by harmful glue and
hardening
accelerator. Examples of this method can be found in U.S. Patents 5,466,152
and 6,318,999.
Therefore, important aspects of dental modeling should include: 1 ) accurate,
stable and
easy repositioning of the sections of the model to their former relationship
with the adjacent dies
and also with the opposing model; and 2) the reliable registration of the
upper and lower
castings with respect to one another.
SUMMARY OF THE INVENTION
It has been recognized that it would be advantageous to develop a dental
modeling and
articulating system and method that makes accurate, precise and fast dental
models from which
dental prosthesis elements, such as crowns, bridges, caps (substructure) for
CAD/CAM
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3
production, inlays, onlays, and other restorative dental works, can be
fabricated. In addition, it
has been recognized that it would be advantageous to develop a dental modeling
and articulating
system with tray support members for dental casts and a built-in articulating
hinge member that
1) maximizes the work efficiency, 2) provides substantially perfect centric,
lateral and protrusive
movements, and 3) permits substantial perfect registration of the dental
casts.
The invention provides a dental articulator device to duplicate at least a
portion of a
patient's mouth for use in producing a dental prosthesis. The device includes
a pair of trays
pivotally coupled together and pivoting with respect to one another between
closed and open
configurations. In the closed configuration, the trays are opposingly spaced-
apart from one
another. In the open configuration, the trays are pivoted away from one
another.
In accordance with one aspect of the present invention, a hinge is integrally
formed with
the trays and positioned between the trays. On one of the trays, the hinge
includes a pivot axle
and a shoulder extending at least partially around the pivot axle, creating
two axle portions
extending on each side of the shoulder. On the other tray, the hinge includes
a pair of fingers
pivotally positioned both 1) on opposite sides of the pivot axle, and 2) on
opposite sides of the
shoulder, so that the fingers are separated by both the axle and the shoulder.
In accordance with another aspect of the present invention, a plurality of
registration pin
holes are formed in at least one of the trays. A thin membrane is disposed
across a registration
pin hole to close off the registration pin hole and resist dental casting
material from substantially
filling the registration pin hole. The thin membrane is breakable by a
registration pin inserted
into the registration pin hole with the registration pin being extendable
through the thin
membrane.
In addition, the invention provides a method for forming a dental model. The
method
includes forming prepped and opposing models of prepped and opposing teeth on
lower and
upper trays of a dental articulator. The prepped model includes a model of a
prepped tooth to
receive a dental prosthesis. The opposing model includes a model of an
opposite tooth opposite
the prepped tooth.
In accordance with one aspect of the present invention, the lower and upper
trays pivot
about a hinge integrally formed with the trays. The hinge includes a first
portion with a shoulder
circumscribing an axle, and a second portion with opposing fingers movably
disposed on
opposite sides of the axle and on opposite sides of the shoulder.
In accordance with another aspect of the present invention, the method
includes pressing
a registration pin through a thin membrane extending across a registration pin
hole on at least
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one of lower and upper trays of a dental articulator so that the registration
pin breaks the thin
membrane and extends through the thin membrane.
Additional features and advantages of the invention will be apparent from the
detailed
description which follows, taken in conjunction with the accompanying
drawings, which
together illustrate, by way of example, features of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 a is a perspective view of a dental articulator of a dental modeling
system in
accordance with an embodiment of the present invention, shown in a closed
configuration;
FIG. lb is an exploded perspective view of the dental articulator of FIG. 1 a,
shown in an
open position and with a negative impression of a patient's teeth;
FIG. 2 is a perspective view of an upper tray of the dental articulator of
FIG. 1 a;
FIG. 3 is a perspective view of the upper tray of the dental articulator of
FIG. 1 a;
FIG. 4 is a top view of the upper tray of the dental articulator of FIG. la;
FIG. Sa is a bottom view of the upper tray of the dental articulator of FIG. 1
a;
FIGs. Sb and c are cross sectional end views of the upper tray of FIG. Sa
taken along
lines Sb-Sb and Sc-Sc respectively;
FIG. 6 is an end view of the upper tray of the dental articulator of FIG. la;
FIG. 7 is a perspective view of a lower tray of the dental articulator of FIG.
1 a, shown
with a prosthesis die;
FIG. 8 is a perspective view of the lower tray of the dental articulator of
FIG. 1 a;
FIG. 9a is a top view of the lower tray of the dental articulator of FIG. 1 a;
FIG. 9b is a detailed view of the lower tray of FIG. 9a;
FIGS. 10 and 11 are bottom views of the lower tray of the dental articulator
of FIG. 1 a;
FIG. 12a is an end view of the dental articulator of FIG. 1 a;
FIG. 12b is an end view of the lower tray of the dental articulator of FIG. 1
a;
FIG. 13 is a cross-sectional end view of the lower tray of FIG. 9a taken along
line 13-13;
FIG. 14a is a cross-sectional end view of the lower tray of FIG. 9a taken
along line 14a-
14a;
FIG. 14b is a detailed view of the lower tray of FIG. 14a;
FIG. 14c is a cross-sectional end view of a lower tray in accordance with
another
embodiment of the present invention;
FIG. 15 is a cross-sectional end view of the lower tray of FIG. 9a, shown with
a
registration pin;
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FIG. 16 is a cross-sectional end view of the lower tray of FIG. 9a taken along
line 16-16;
FIG. 17 is a side view of the dental articulator of FIG. 1 a, shown with
dental casts;
FIG. 18 is a side view of the dental articulator of FIG. 1 a;
FIG. 19a is a schematic view of a lower tray of a dental articulator in
accordance with an
5 embodiment of the present invention;
FIG. 19b is a detailed view of the lower tray of FIG. 19a;
FIG. 20a is a schematic side view of the dental articulator of FIG. 1 a, shown
with dental
casts;
FIG. 20b is a schematic cross-sectional end view of a lower tray of the dental
articulator
of FIG. 1 a, shown with a prosthesis die;
FIG. 20c is a detailed view of a lower tray of the dental articulator of FIG.
20a;
FIG. 21 is a partial exploded top view of the dental articulator of FIG. 1 a;
FIG. 22 is a partial exploded side view of the dental articulator of FIG. 1 a;
FIG. 23 is a partial perspective view of the lower tray the dental articulator
of FIG. 1 a;
FIG. 24 is a partial exploded side view of the dental articulator of FIG. 1 a;
FIG. 25 is a partial perspective view of another hinge part in accordance with
the present
invention;
FIG. 26 is a partial exploded side view of another hinge part in accordance
with the
present invention;
FIG. 27a is a partial exploded perspective view of the dental articulator of
FIG. 1 a;
FIG. 27b is partial perspective view of the dental articulator of FIG. 1 a;
FIG. 28 is a partial perspective view of the dental articulator of FIG. 1 a;
FIG. 29 is a schematic end view of the dental articulator of FIG. 1 a;
FIG. 30a is a top view of another dental tray of another dental articulator of
another
dental modeling system in accordance with another embodiment of the present
invention;
FIG. 30b is a cross-sectional end view of the tray of FIG. 30a;
FIG. 30c is a detail view of the tray of FIG. 30b; and
FIG. 30d is a cross-sectional end view of another embodiment of a tray in
accordance
with the present invention.
DETAILED DESCRIPTION
Reference will now be made to the exemplary embodiments illustrated in the
drawings,
and specific language will be used herein to describe the same. It will
nevertheless be
understood that no limitation of the scope of the invention is thereby
intended. Alterations and
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further modifications of the inventive features illustrated herein, and
additional applications of
the principles of the inventions as illustrated herein, which would occur to
one skilled in the
relevant art and having possession of this disclosure, are to be considered
within the scope of the
invention.
As illustrated in FIGS. 1-29, a dental modeling and articulating system or
device,
indicated generally at 10, and its component parts, in accordance with the
present invention is
shown for use in producing a dental model that is a substantial duplicate of a
patient's mouth for
use in the production of dental prostheses. Such dental prostheses can include
crowns, bridges,
caps (substructure) for CAD/CAM production, inlays, onlays and other
restorative dental works.
The dental modeling and articulating system 10 includes a pair of trays, such
as upper and lower
trays 1 l and 12, that are pivotally coupled together. The trays 11 and 12
have die receiving
surfaces, such as respective upper and lower die receiving surfaces 13 and 14.
The trays 11 and 12, or die receiving surfaces 13 and 14, receive dental
casting material,
and dies or models of a patient's teeth. The lower tray 12 and lower die
receiving surface 14 can
receive a prepped model 15 or lower cast (FIGs. 17 and 20a) of one or more
prepped teeth of a
patient. The prepped model 15 can include a model of a prepped tooth, or
prosthesis die 16
(FIGS. 17 and 20a), to receive a dental prosthesis. Thus, the lower tray 12
and lower die
receiving surface 14 receive the prepped model of the tooth that will be
worked on. The upper
tray 11 and upper die receiving surface 13 can receive an opposing model 17 or
upper cast
(FIGs. 17 and 20a) of one or more opposing teeth of a patient that oppose the
prepped teeth.
The opposing model 17 can include a model of an opposite tooth opposite the
prepped tooth.
It should be noted that the designation or description of the trays and die
receiving
surfaces as being "upper" and "lower" does not necessarily correspond to the
patient's upper and
lower teeth. The lower tray can be the working or prepped tray and can receive
the prepped
model 15 (FIGS. 17 and 20a), which can correspond to either the patient's
upper or lower teeth.
As the working or prepped tray, it is typically most convenient to position
the tray as the lower
tray. Similarly, the upper tray can be the opposing tray and can receive the
opposing model 17
(FIGs. 17 and 20a). It will be appreciated that the upper and lower trays can
have different
configurations, as shown, or can have similar or the same configurations.
Because a majority of
dental cases require prosthetics or the like for only the upper or lower side
of the mouth, it is
typically only necessary to have one lower or working tray. In cases where
both the upper and
lower side of the mouth require prosthetics or the like, then two lower trays
can be coupled
together.
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The trays 11 and 12 can pivot with respect to one another between a closed
configuration
and an open configuration. In the closed configuration, the trays 11 and 12
generally oppose
one another and are spaced apart from one another, as shown in FIG. 1 a. The
die receiving
surfaces 13 and 14 oppose one another in the closed configuration. In the open
configuration,
the trays 11 and 12 can pivot away from one another, as shown in FIG. lb. The
closed
configuration corresponds to, or models or imitates, a patient's closed mouth,
and the dies or
models of the patient's teeth close against one another (as shown in FIG. 17).
The open
configuration allows the dies or models of the patient's teeth to be separated
for producing
dental prostheses and the like. In addition, the trays 11 and 12 can be
detachably connected to
allow the trays to be separated. The trays may be provided separately (as
shown in FIG. lb),
and connect during or before use.
The trays 11 and 12 can include a pair of arms, or lower and upper arms 18 and
19, each
extending from one of the trays to a hinge 20. Thus, the arms 18 and 19 can
maintain the trays
11 and 12 in a spaced-apart relationship in the closed configuration. The
lower arm 18 can
extend upwardly and rearwardly, while the upper arm 19 can extend downwardly
and
rearwardly. Thus, the hinge can be positioned behind the tray. In addition,
the lower arm 18
can include a pair of lower arms 18a and 18b, and the upper arm can include a
pair of upper
arms 19a and 19b. Thus, the device 10 can include a pair of hinges 20a and
20b, each disposed
between a different pair of arms. The lower arms 18a and 18b and the upper
arms 19a and 19b
can also extend laterally outwardly from the trays 11 and 12 so that the pair
of hinges 20a and
20b are spaced-apart from one another. The spaced-apart hinges 20a and 20b can
provide
additional stability to the movement of the trays. The trays and arms can be
integrally formed.
The trays 11 and 12, and the arms 18 and 19, are pivotally and detachably
connected by
the hinge 20. The hinge 20 is positioned between the trays 11 and 12, and
between the arms 18
and 19. In addition, the hinge 20 is integrally formed with the trays 11 and
12, and thus with the
arms 18 and 19. A portion of the hinge 20 can be carried by each tray or arm.
Thus, the hinge
can be a two-part hinge with one part formed with the lower tray and lower
arm, and the other
part formed with the upper tray and upper arm. In addition, the hinge 20 or
parts thereof can
snap together for use (as shown in FIG. 1 a). The hinge 20 or trays 1 l and 12
can be separated if
necessary (as shown in FIG. lb). The arms 18 and 19 and hinge 20 allow the
device 10 to
mimic or model the open and closing function of a mouth.
Referring to FIGs. 21-29, the hinges 20a and 20b each can include a pivot axle
22a and
22b. The pivot axles can be aligned or collinear. A shoulder 24 can extend at
least partially
around each pivot axle 22a and 22b dividing the pivot axle and creating two
axle portions
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extending from each side of the shoulder 24. The shoulder 24 can circumscribe
or extend
entirely around the axle 22a and 22b, as shown. In addition, the shoulder 24
can extend between
the arm and the axle to attach the axle to the respective arm. The axle and
shoulder can form a
first part of the hinge. The second part of the hinge can include a pair of
fingers 26a and 26b
that extend from another arm and that pivotally engage and hold the first part
of the hinge. The
fingers 26a and 26b can grip both the axle 22a and 22b and the shoulder 24.
Thus, the fingers
26a and 26b can be pivotally positioned on opposite sides of the axle 22a and
22b, and on
opposite sides of the shoulder 24. The forgers 26a and 26b can bear against
the axle and the
shoulder in a slidable fashion. Thus, the hinge provides a solid or firm feel,
and resists undue
movement between the trays. It has been found that such a hinge 20 permits
limited movement
of the upper tray 11 with respect to the lower tray 12 to simulate the natural
movements of the
human jaw, including centric, lateral and protrusive movements.
The fingers 26a and 26b, or inner surfaces thereof, can be arcuate or curved
with the
curvature oriented in a plane orthogonal to the pivot axle. Thus, the fingers
can curve about the
axle. In addition, the fingers 26a and 26b can define a pivot opening 28
therebetween to receive
the pivot axle 22a and 22b. Thus, the pivot opening 28 can be circular to
receive the circular
shape of the pivot axle. Furthermore, a gap 30 can be formed between distal
ends of the fingers
26a and 26b and can define an entrance to the pivot opening 28. The gap 30 can
be narrower
than the pivot opening 28 so that the axle 22a and 22b can be inserted through
the gap 30 and
into the pivot opening 28, and the axle can be maintained in the pivot
opening. The gap 30 can
be tapered, or can narrow, with a wider entrance to receive the axle. In
addition, the fingers can
be relatively flexible, so the size and material of the fingers can allow the
distal ends of the
fingers to separate at the gap 30 to allow the axle to be pressed into and
pulled out of the pivot
opening 28 under force, but maintain the axle in the pivot opening during use.
In addition, the
fingers 26a and 26b can be laterally spaced-apart to form a space 32
therebetween to receive the
shoulder 24 therein.
A curved channel 34 can circumscribe at least a portion of the pivot axle 22a
and 22b, as
shown in FIG. 24. As the trays 11 and 12 pivot with respect to one another,
one of the fingers
26a or 26b can move within the curved channel 34. It is believed that the
curved channel
provides further support and rigidity to the hinge. The finger can be in the
channel 34 in the
closed configuration to hold the finger in the channel, but can be out of the
channel in the open
configuration so that the trays can be separated.
Stops 36a and 36b can be formed on the hinge 20 or the arms 18 and 19 and
positioned
to abut when the trays are in the closed configuration to maintain the trays
in the proper position.
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The hinge 20, or parts thereof, can be formed integrally with the firays 11
and 12 and
arms 26a and 26b, thus eliminating the usage of harmful glues and hardening
accelerators.
The hinge 20 allows the upper tray 11 to be movable toward and away from the
lower
tray 12. Thus, with the dental casts 15 and 17 on the lower and upper trays
(as shown in FIGs.
17 and 20a), it is possible to simulate the opening and closing movement of a
patient's jaw. In
addition, it is possible to pivot the upper tray 11 away from the lower tray
during work on the
lower cast 15.
The lower arms 18a and 18b can each have different or opposite parts of the
hinge 20, as
shown in FIGs. 7 and 8. For example, one of the arms 18a can include the pair
of fingers 26a
and 26b, while the other of the arms 18b can include the pivot axle 22 and
shoulder 24.
Similarly, one of the upper arms 19a can include the pivot axle 22 and
shoulder 24, while the
other of the arms 19b can include the pair of fingers 26a and 26b, as shown in
FIGS. 2 and 3.
Thus, a pair of lower trays 12 can be coupled together.
In addition, one or both or the trays, such as the lower tray 11, can include
an array of
registration pin holes 40 for receiving registration pins 42 that are secured
to the casts, as shown
in FIG. 7. The registration pin holes 40 can be arrayed in a single row
aligned with a longitude
of the tray, and positioned in a center of the tray. The registration pin
holes 40 and the
registration pins 42 can be slightly tapered to help seat and secure the pins
in the holes so that
there is substantially no play or movement between the two. The registration
pin holes taper
inwardly extending into the tray from the die-receiving surface. The
registration pin holes 40
can be evenly spaced and arranged in rows extending parallel to the rows of
registration struts
described below. Additional registration pin holes 41 can be formed at a free
end of the tray to
embrace either the left or right side of the upper and lower dental arch. The
additional
registration pin holes 41 at the free-end can be configured for curved aspects
of the impression
for anterior teeth.
Referring to FIGs.l 5 and 20, a registration pin 42 can be placed into a
registration pin
hole 40 or 41. The registration pin 42 can be a brass dowel pin with a head
portion that has a
knurled outer surface that can be embedded into the molded cast or model 15
(FIG. 17 and 20a).
The other end of the registration dowel pin can be a base portion that has a
smooth outer
cylindrical or frusto-conical surface that is inserted into and removed from
the registration pin
hole 40 or 41. FIG. 20 shows a side view wherein the tray support members 11
and 12 have
been pivotally rotated in relationship to one another. Registration pins 42
have been placed in
the registration pin holes 40 and 41. Casting material has been poured into
place on the bed of
the tray.
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Referring to FIGs. 8, 10, 11, 14-16 and 20, rounded and recessed thumb
indentations 43
can be centered at a bottom of the registration pin holes 40, or near the
bottom of the tray. The
thumb indentations 43 can have a depth to receive a distal end of the
registration pin 42 when
inserted into the registration pin hole 40. The thumb indentations 43
accommodate the finger or
5 thumb tips of the technician's hand to push the pins 42 from the
registration pin holes 40, and
thus the prosthesis die 16 from the tray. The thumb indentations 43 allow the
technician to push
up softly and smoothly on the tip of the registration pin 42, thereby easily
removing the
prosthesis die 16 and prosthesis work thereon. The thumb indentations 43 can
be especially
usefizl when, at the initial stage of porcelain build up which is still in wet
condition, the
10 prosthesis die 16 needs to be removed from the tray, as well as for
subsequent engagement and
disengagement of the prosthesis die 16 to and from the lower tray that is
being worked on. It
will be understood that when the wet porcelain is not in solid condition, the
porcelain is fragile.
The thumb indentations 43 facilitate the removal of the registration pins 42
from the registration
pin holes 40, and thus the removal of prosthesis work from the prosthesis die
16 (or
working/master die) at an initial stage of porcelain build up.
Referring to FIGs. 14a and 14b, a thin membrane 44 advantageously can be
disposed
across one or more of the registration pin holes 40. The thin membrane 44 can
close off the
registration pin holes 40 or 41 and resist dental casting material from
substantially filling the
registration pin holes, as discussed below. The thin membrane 44 can include a
material and
thickness that is breakable or piercable by the registration pin 42 when
inserted into the
registration pin hole, and/or forced against the thin membrane. The membrane
44 can be of
sufficient thickness to close the holes 40 and 41, and can be of sufficient
thinness to be easily
pierced by inserting and pushing the registration pin 42 with finger tips from
the side of the die-
receiving surface to the bottom surface of the tray. Alternatively, a tool or
the like can be used
to push the pin through the membrane. The thin membrane can have a thickness
in the range of
0.002 ~ 0.003 inches (0.06 ~ 0.08 mm).
In addition, the thin membrane 44 can be positioned, and the registration pin
42, can be
sized, so that the registration pin 42 extends through the thin membrane 44.
The thin membrane
44 can be formed of the same material as the tray, and can be formed
integrally with the tray.
The thin membrane 44 can be positioned near a bottom of the registration pin
holes 40 and 41.
For example, the thin membrane 44 can be positioned between the registration
pin holes 40 and
the thumb indentations 43. Such a location near the bottom of the registration
pin holes 40 and
41 can facilitate manufacture during an injection molding process.
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Alternatively, as shown in FIGs. 14c, 19a and 30d, the thin membrane can be
positioned
as desired, such as at a top of the registration pin holes 40 and 41, and at
the die receiving
surface 14. For example, a thin membrane 44b can be separately formed from the
tray, and
attached to the tray. Such a thin membrane 44b can be attached to the die
receiving surface at
the top of the registration pin holes 40 and 41. The thin membrane 44b can be
attached by
adhesive, sonic welding, etc.
The thin membrane 44 or 44b can close the registration pin holes 40 and 41 and
can
provide a distinct advantage over open registration pin holes. For example,
open registration pin
holes allow the semi-liquid casting material to creep into the holes when the
negative impression
filled with this casting material is inverted onto the tray. The casting
material can get stuck in
the hole when it hardens, making the initial release of the segmented dies
from the tray support
members an arduous and difficult job. The closed registration pin holes,
however, are closed at
one end by a thin membrane, creating an air pocket in the hole when the
impression filled with
casting material is inverted onto the tray. The air pocket resists the casting
material from
creeping into the registration pin hole, thus making the removal of the dies
easy and clean, and
eliminating the initial die breakage off the tray. The absence of the tiny
debris of casting
material from the initial breakage, and from subsequently repeated engagement
and
disengagement of the prosthesis dies to the tray, keeps the die receiving
surface of the tray clean
at all times, and allows positive, accurate, and solid re-registration of the
segmented dies onto
the tray support member, thus resulting in proper spatial relationship of the
segmented dies with
respect to the remainder of the dental cast.
As stated above, the lower tray 12 can be the working tray, or the tray to
receive the
prosthesis die 16 which is a model of the tooth to be worked on; while the
upper tray 11 can be
the opposing tray that receives the opposing model 17. Thus, the lower tray 12
can receive the
model of either the upper or lower teeth of the patient. The trays can have an
elongated,
rectangular shape to receive models of one side of a user's teeth. Referring
to FIG lb, the upper
tray 11 can be simpler in design, structure and function compared to lower
tray 12. Cases that
require prosthesis dies on both the upper and lower teeth at the same time are
rare. Clinically,
less than 3 cases out of 100 cases need prosthesis work for both upper and
lower teeth at the
same time. If prostheses must be prepared for both upper and lower teeth, then
two lower trays
12 can be connected together. Otherwise, a simpler upper tray 11 will often
suffice to hold the
upper cast or opposing model with a tight grip. The upper die-receiving
surface 13 of the upper
tray 11 can have a recessed trough formed therein with a perimeter wall 48
extending around the
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tray and forming the trough. Gripping struts 50 can be formed on the surface
13 of the upper
tray 11 to help hold the cast with internal stability after the casting
material hardened.
As show in FIGS 1 a, 7 and 20 a, the lower tray 12 can include a trough formed
by a
perimeter wall 52 and into which casting material can be poured. The perimeter
wall 52 (and
48) can have a wavy profile, or an inner surface with a wavy cross-section.
The wavy profile
can include a plurality of curved or arcuate indentations to form curved or
arcuate protrusions in
the casting material or models. It has been found that the curved, convex
protrusions in the
casting material are less susceptible to breaking or chipping. Broken or
chipped portions of the
casting material can inadvertently lodge between the tray 12 and the sectioned
dies 15-16
preventing proper repositioning of the sectioned dies. The rounded walls can
provide a distinct
advantage over notched-edge or saw-like serrations by reducing the breakage
and wear from the
repeated re-positioning of the prosthesis dies while being worked on. In
addition, the wall 52
maintains and holds the dies while offering minimal retention resistance,
thereby eliminating the
use of extra accessories like releasing devices, stands, mallets, etc. that
are needed in other
systems.
Referring to FIGS. 7 and 9a, the angle of the wall 52 in the lower tray 12 can
be wider for
easier release of a segmented die 15-16 (FIG. 20a). In addition, the lower
tray 12 can include
registration struts 56 disposed on the die-receiving surface 14 and arrayed
from the free end to
the hinged end. The registration struts 56 can have a hexagonal cross-section.
It has been found
that the hexagonal cross-section of the registration struts 56 can help
maintain the proper
aligrunent of the segmented die 15-17. Smaller struts can be located near the
free end, while
larger struts can be located near the hinge end. The smaller struts can be
smaller in diameter
than the registration pin holes. The registration struts can taper inwardly
and upwardly along a
length of the strut, and can form internally retentive concavities in the
cast. The center of each
strut can be laterally aligned with a center of corresponding and adjacent
registration pin holes.
The alignment of the struts with the registration pin holes allow each
segmented cast or die to
have at least one pin, and one or more struts, even for the small teeth like
bicuspids. Thus, the
casts can be segmented with the struts and concavities in whole, and not
partially sawed apart
from the adjacent segments, resulting in maximum registration stability
without mesial and
distal movement, even for the small teeth like bicuspids. The bigger struts
located at the hinge
side are allocated for molars, and the smaller struts are for small teeth,
like bicuspids, canines
and anterior teeth. Bigger struts can be evenly spaced, wider apart, and
smaller struts can be
evenly spaced, narrower apart. Except for the presence of the registration
struts and registration
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13
holes, the die-receiving surface 14 can be essentially flat and can form a
stable planar base for
receiving casting stone material thereon for forming a dental cast.
Referring to FIGS. 1-2 andl8, a hole 60 can be formed in one of the trays or
arms, while
a receiving area 62 can be formed in the other of the arms or trays. The hole
60 and receiving
area 62 can be formed in a jointing area between the tray and the arms. A
posterior vertical stop
rod 64 can be received through the hole 60 and can abut to the receiving area
62. The posterior
vertical stop rod 64 can be secured in the hole 60 so that the rod can
increase stability for cases
with non-supporting tooth abutment against the opposing cast.
While the above has described devices and methods suited for quadrant
impression
modeling, similar devices and methods can be configured for full-arch
impression modeling, as
shown in FIGs 30a-c. All the characteristics found in quadrant upper tray 11
and lower tray 12
are reflected in a full-arch tray 90. The full-arch tray 90 can include upper
and lower tray
support members that are U-shaped to accept impression molds of the patient's
entire mouth.
A method for forming a dental model, and for using the system or devices 10 or
90
described above, includes forming a prepped model 15 of prepped teeth on the
lower tray 12,
and forming an opposing model 17 of opposing teeth on the upper tray 11, of a
dental articulator
10 or 90. The prepped model 15 includes a model of a prepped tooth to receive
a dental
prosthesis, while the opposing model 17 includes a model of an opposite tooth
opposite the
prepped tooth. Forming the models 1 S and 17 can include obtaining an
impression 100 (FIG.
lb) of at least some of a patient's teeth. The impression 100 can typically be
made by a dentist
by placing a formable material onto a tray or the like, and having the patient
bite into the
formable material, thus leaving a negative impression of the patients teeth,
as is known in the
art. The impression includes a prepped side with an impression of the prepped
tooth to receive a
dental prosthesis, and an opposing side with an impression of the opposing
tooth opposing the
prepped tooth. Such an impression can typically be provided to the technician.
The impression can be disposed between the upper and lower trays 11 and 12 of
the
dental articulator 10 or 90. Dental casting material can be introduced between
the upper tray 11
and the opposing side of the impression 100 to form the opposing model 17 of
the opposing
tooth. For example, dental casting material can be disposed on the upper tray
11 and in the
opposing side of the impression 100. The opposing side of the impression 100
can be disposed
over the upper tray 11 so that dental casting material extends therebetween,
and forms the
opposing model 17 of the opposing tooth. The side of the impression 100 that
has a prepared
tooth typically faces the lower tray 12. Thus, regardless of whether the upper
teeth or lower
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14
teeth are to receive a dental prosthesis, the lower tray 12 typically receives
the prepped side of
the impression 100.
Similarly, dental casting material can be introduced between the lower tray 12
and the
prepped side of the impression 100 to form the prepped model 15 of the prepped
tooth. For
example, the dental casting material can be disposed on the lower tray 12 and
in the prepped side
of the impression 100. The lower tray 12 can be disposed over the prepped side
of the
impression 100 so that the dental casting material extends therebetween, and
forms the prepped
model 15 of the prepped tooth. The impression 100 can be removed from the
dental articulator
or 100 leaving the opposing and the prepped models 17 and 15 on the respective
upper and
10 lower trays 11 and 12.
The impression 100 can first be inverted over the upper tray 11 and the
opposing model
17 can be formed first. The impression 100 can then be inverted over the lower
tray 12, while
still attached to the opposing model 17 and upper tray 11, to form the prepped
model 15. Thus,
the resulting prepped and opposing models 15 and 17 can be mounted in the
dental articulator
with the bite exactly as the impression provided by the dentist.
Alternatively, the prepped model
can be formed first, and the opposing model can be formed after.
The prepped model 15 can be segmented on sides corresponding to the prepped
tooth to
form the prosthesis die 16. Thus, the upper and lower trays 11 and 12 receive
respective upper
and lower casts, or opposing and prepped models 17 and 15 (as shown in FIG. 20
a). In
practice, the dental technician cuts the cast 15 and/or 17 to separate out and
form the master or
prosthesis die 16 to be worked on. The model 15 and/or 17 can be cut into
segments so that
each segment has at least one registration pin 42 (or no pins at all if
preferred), and at least two
internally retentive cavities corresponding to at least two registration
struts 56. Segments can be
removed and reinserted into their precise location on the tray to reproduce
the model of the
original impression and the relationship of the upper and lower tray with
respect to each other.
In accordance with one aspect of the invention, a dental articulator 10 or 90
can be
obtained with upper and lower trays 11 and 12 pivotally coupled together by
the hinge 20 that
can be integrally formed with the trays. The hinge can include a first portion
with a shoulder 24
substantially circumscribing a pivot axle 22, and a second portion with
opposing fingers 26a and
26b movably disposed on opposite sides of the axle 22, and on opposite sides
of the shoulder 24.
The lower and upper trays 11 and 12 can be pivoted about the hinge 20 that is
integrally
formed with the trays. Thus, the upper tray 12 can be pivoted to the open
configuration to allow
access to the prosthesis die 16. In addition, the upper tray 12 can be pivoted
to the closed
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configuration to check for clearance between the dental prosthesis on the
prosthetic die 16 and
the opposing model 17.
In accordance with another aspect of the invention, a dental articulator 10 or
90 can be
obtained with a thin membrane 44 or 44b extending across registration pin
holes 40 and/or 41 in
5 at least one of the trays, such as the lower tray 12. Registration pins 42
can be positioned in
registration pin holes 40 and/or 41 in one of the trays, such as the lower
tray 12. For example, at
least one registration pin 42 can be positioned at a location corresponding to
the prepped tooth
and the prosthesis die 16. In addition, other registration pins can be
positioned on either side of
the prosthesis die 16. The pins can be located to the best advantage in
working with the dental
10 model. The registration pin 42 can be pressed through the thin membrane 44
and/or 44b
extending across the registration pin hole 40 and/or 41 so that the
registration pin breaks the thin
membrane and extends through the thin membrane. As described above, the thin
membrane can
be positioned near the bottom of the registration pin hole, or at the top of
the registration pin
hole.
15 The prepped model 15 of the prepped tooth can be formed over the
registration pin 42 on
the tray 12 of the dental articulator. For example, the dental casting
material can be poured over
the registration pin 42. In addition, the dental casting material can be
disposed over the
registration pin holes 40 and/or 41 with the thin membrane 44 and/or 44b
formed integrally with
the tray and extending across the registration pin holes to resist dental
casting material from
substantially filling the registration pin holes.
In accordance with another aspect of the present invention, the dental casting
material
can be disposed around the registration struts 56 in at least one of the
trays, such as the lower
tray 12. As described above, the registration struts 56 can have a hexagonal
cross section
forming a hole in the prepped model 15 and the prosthesis die 16 that also has
a hexagonal cross
section. The hexagonal cross section of the struts and hole mate to resist
movement of the
prepped model 1 S and the prosthesis die 16, and to properly orient and
position the prepped
model 15 and the prosthesis die 16 in the tray 12.
In accordance with another aspect of the present invention, the dental casting
material
can be disposed in at least one of the trays 11 and/or 12 with a trough formed
by a perimeter
wall 48 and/or 52. The perimeter wall 48 andlor 52 can have a wavy profile
with a plurality of
arcuate indentations. The wavy profile creates a mating wavy profile in the
models 15 and 17
and the prosthesis die 16 to properly orient the models and die in the trays.
In addition, the
curved indentations form curved protrusions in the models 15 and 17 and die 16
that resist
chipping, and thus resist debris interfering with the fit between the trays
and the models and die.
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16
The dental casting material can be disposed in the trays 11 and 12 and the
impression
100 by pouring the dental casting material while it is in a semi-liquid state.
After the dental
casting material substantially hardens, dries, and/or solidifies, the
impression 100 can be
removed.
A "re-articulating" technique can be accomplished with the present system by
softening
the material of the arm by lightly heating one set of the articulating arms
with a micro-torch and
then setting the correct bite by hand while the articulating arms are still
hot. The arms harden in
the correct position as the material cools.
It is to be understood that the above-referenced arrangements are only
illustrative of the
application for the principles of the present invention. Numerous
modifications and alternative
arrangements can be devised without departing from the spirit and scope of the
present
invention. While the present invention has been shown in the drawings and
fully described
above with particularity and detail in connection with what is presently
deemed to be the most
practical and preferred embodiments(s) of the invention, it will be apparent
to those of ordinary
skill in the art that numerous modifications can be made without departing
from the principles
and concepts of the invention as set forth in the claims.
